<!DOCTYPE html>
<html lang="zh_cn">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>用户注册页面</title>
</head>
<body>

输入完用户名后校验只能是"admin"，否则弹框提示错误
点击提交执行后执行事件，把自我介绍的内容弹框提示出来
<div>
    <form action="xxx">
        <p>用户名：<input type="text" id="username" onblur="checkUsername()"></p>
        <p>密码：<input type="password" ></p>
        <p>性别：<input type="radio" name="sex">男 <input type="radio" name="sex">女</p>
        <p>学历：<select name="xueli">
                <option value="benke">本科</option>
                <option value="zhuanke">专科</option>
            </select>
        </p><br/>
        <p>自我介绍：<textarea id="introduction"></textarea></p>
        <button type="submit" id="submit" onclick="submitbbb()">提交</button>
        <button type="reset" name="resetzhuce">重填</button>
    </form>
</div>
<script>
    function submitbbb() {
        var introduction = document.getElementById("introduction").value;
        alert("自我介绍："+introduction);

    }
    
    function checkUsername() {
        var name = document.getElementById("username").value;
        if (name != "admin") {
            alert("用户名错误，请输入正确的用户名admin！");
        }
    }
</script>
    
</body>
</html>